The eco-hydrology of glacier surfaces

• Main Author: Stevens, Ian
• Format: Book
• Language: English
• Published: 2019
• Subjects: Arctic
• Online Access: https://pure.au.dk/portal/da/publications/the-ecohydrology-of-glacier-surfaces(9de168ed-fe8a-452d-aa00-f69c8079c6d4).html

Recent work has highlighted the importance of the so-called “weathering crust” as a microbially and hydrologically active layer on glacier surfaces. However, this layer is yet to undergo investigation, with no estimates of water, microbial or nutrient fluxes through it to downstream freshwater and marine ecosystems. The mechanics of the weathering crust, and its role in transport and/or retention of particulate impurities at the glacier surface presents a research imperative. To investigate the eco-hydrology of glacier surfaces, this thesis presents a dataset collected at eleven sites in the Northern Hemisphere from the Canadian Arctic to the European Alps, collected between 2014 and 2016. To interrogate this dataset, the study develops and tests a novel logging piezometer which is used to calculate mean weathering crust hydraulic conductivity at all locations of 0.184 m d-1, equivalent to a sandstone, and meltwater velocities of 10-1 m d-1. This hydrologically poor aquifer, causes the storage of water at the surface for tens of day, providing an ideal medium for biogeochemical cycling. For microbial cell enumeration, a flow cytometry protocol is presented which is suitable for glacial environments providing accurate, reliable cell counts. Across the eleven sites, mean microbial cell concentration in weathering crust meltwater was revealed to be ≈ 104 cells mL-1 . It was unclear what controls exist upon cell concentrations in the weathering crust, however no links between weathering crust hydraulic conductivity, electrical conductivity or water temperature and cell concentrations were observed. Cellular particulate organic carbon flux (POC) form this active environment contributes a minimum of 1.1 Tg of cellular carbon per year to downstream freshwater and marine environments per year.